The present invention relates to an apparatus for producing containers made of paper-base laminate and filled with contents such as fluid food.
Such containers have a closed bottom portion generally bulging outward, are therefore not positionable upright with good stability but tend to rock, and can not be displayed in a stable position. Further when allowed to rock, the container becomes damaged at the corners of the closed bottom portion.
To overcome the above problem, the present applicant has already proposed a container having a bottom portion which is recessed in the form of a pyramid centrally thereof, and an apparatus for producing the container (see U.S. Pat. No. 4,838,847).
The container proposed by the present applicant is positionable with good stability, whereas the liquid level within the container rises by an amount corresponding to the bottom recess of the container. The liquid is then likely to spill from the container during transport. This must be prevented by reducing the transport speed of the container transport conveyor, consequently entailing the problem of impairing the efficiency of the packaging machine.
On the other hand, the container producing apparatus has mandrels and a pressure bonding member. To form the recessed bottom portion, each of the mandrels needs to be formed in its forward end face with a cavity defined by a pyramidal recessed surface, and the bonding member has a pressing face which must be provided with a projection corresponding to the cavity. However, the cavity and the projection are not easy to make, necessitating an increased machining cost.